1,3-Cyclobutanediones (dialkyl ketene dimer) reacted with various aromatic aldehydes to give six-membered cyclic β-keto esters by using a catalytic amount of potassium ethoxide. Effects of alkoxide catalysts and spiro cyclic groups at the 2,4-positions of 1,3-cyclobutanediones were investigated.
3-Aryl-2-hydroxy-2,2-dimethyl-propansäureethylester und 6-Aryl-3,3,5,5-tetramethyl-tetrahydropyran-2,4-dione
作者:Bernard Unterhalt、Klaus Weyrich
DOI:10.1002/ardp.19803130912
日期:——
Hydroxyketone 2, die in die dem Clofibrat ähnlichen substituierten Propansäureethylester 5 überge‐führt werden sollten. Da der direkte Syntheseweg fehlschlug, wurden aromatische Aldehyde mit 4 grignardiert und ergaben sowohl 5 als auch Tetrahydropyran‐dione 6.
Powerful Claisen condensation and Claisen–aldol tandem reaction of α,α-dialkylated esters promoted by ZrCl4–iPr2NEt
作者:Yoo Tanabe、Ryota Hamasaki、Syunsuke Funakoshi
DOI:10.1039/b104185c
日期:——
Powerful Claisenestercondensations of α,α-dialkylated esters mediated by ZrCl4–iPr2NEt were performed to give the corresponding thermodynamically unfavorable α,α-dialkylated β-ketoesters, and Claisen–aldol tandem reactions between an intermediary Zr-enolate of a α,α-dialkylated β-ketoester and aldehydes also proceeded.